In a related art network system, an action of each of switches respectively located at an ingress and an egress of a network is implemented as an action (Action) resulted from a search of a single table. That is, each of the above-mentioned switches, searches the table having entries each including a search key, an action, and so forth with respect to an input packet, and performs an operation specified in an action field corresponding to the key that matches (match) header information of the packet.
The table at the above-mentioned switch includes entries each includes three types of information of {Search key, Action, and Statistical Information}. Though no particular limitation is imposed, an outline of {Search key, Action, and Statistical information} is as follows.
TABLE 1SearchMatching is Possible by Using Combination of ArbitraryKeyHeader Information for Layer 1 (L1) to Layer 4 (L4):Ingress port (Physical Port Number of Switch:L1)/Src MAC(Transmission Source MAC (Media Access Control)Address:L2)/Dst MAC (Destination MAC Address:L2)/Ethertype (Type of Ethernet (Registered Trademark):L2)/VLAN ID(Virtual Local Area Network ID:L2)/VLAN priority (Value ofVLAN PCP (Priority Code Point) (CoS (Class OfService)):L2)/Src IP (Transmission Source IP (InternetProtocol) Address:L3)/Dst IP(Destination IP Address:L3)/IPprotocol (IP Protocol Type)/IP ToS (Upper 6 bits) (ToS (TypeOf Service:1 Byte) Information of IP)/Src Port (TCP(Transmission Control Protocol)/Transmission Source PortNumber of UDP (User Datagram Protocol):L4)/Dst Port(Destination Port Number of TCP/UDP:L4)ActionPacket Relay/Discard, Rewriting of Header Information, orthe Like is Possible:Forward (Output from a Physical Port)/All(Output from AnyPort Except Input Port)/Controller (Output to Controller)/Local (Output to Local Stack of Own Apparatus)/Table(Output According to Content in OpenFlow Table)/In_port(Output from Input Port)/Normal (Output Using Content inLegacy Table)/Flood (Output from Any Port Except Input Portand Block Port of Spanning Tree)/Drop (DiscardPacket)/Modify-Field (Rewriting of Packet HeaderInformation: VLAN ID, Vlan priority, Src MAC, Dst MAC,Src IP, Dst IP, IP Tos, Src Port, and Dst Port areRewritable)StatisticalVarious Types of Statistics are Obtainable for Each Table, forInforma-Each flow, for Each Physical Port, and for Each Queuetion(Queue)
As packet header conversion based on referencing of tables, Patent Literature 1 discloses a configuration for autonomously controlling, by hardware, each internal path which is set in an IP-over-ATM (Asynchronous Transfer Mode) switch. Based on a combination of destination information detected by destination information detection means and input source information, internal conversion means in each sub-unit on an input side searches an internal path table for information including a corresponding internal path identifier. The internal conversion means converts a header included in a series of ATM cells by using the information (including a corresponding internal path identifier) and supplies the converted header to a switch circuit. At each sub-unit on an output side, conversion management means prepares a header conversion table based on the information concerning paths between respective nodes and uses the header conversion table for a header conversion process by header conversion means.
As a configuration including a plurality of tables, Patent Literature 2 discloses a configuration in which a routing information table is constituted from a plurality of sub-tables in a packet forwarding apparatus configured to forward an input packet to an output line specified by a routing processing unit, for example. Each sub-table includes an entry of a first format indicating routing information. At least one of the sub-tables includes, in addition to the entry of the first format, an entry of a second format specifying a different sub-table to be referred to. When the routing processing unit refers to the sub-table specified by an input line interface and the entry of the second format is retrieved, the routing processing unit refers to the different sub-table specified by the entry, thereby executing routing and header conversion of the input packet.
Further, as a configuration including a plurality of tables arranged in multiple stages, Patent Literature 3 discloses a configuration in which a header extraction and search method determination unit generates a search key from header information of a packet, in response to an address search instruction. In this configuration, when a multiple-stage table search unit searches a plurality of address information tables using the search key to detect presence of an internal header, the multiple-stage table search unit transmits an internal header extraction instruction to the header extraction and search method determination unit. The multiple-stage table search unit searches a corresponding one of the address information tables using a search key to transmit information on header addition or deletion to a header conversion unit. The header conversion unit performs a process of the header addition or deletion for the packet and transmits a packet transmission instruction to a packet transmission unit.
Patent Literature 4 discloses a network node apparatus including a forwarding table, an address conversion table, and a routing information table. One memory address is retrieved from the forwarding table, using the destination address of a received packet as a search key, and routing information is retrieved from the routing information table, based on an entry address obtained by conversion by the address conversion table.
Patent Literature 5, there is disclosed a self-routing type switching equipment including a label conversion circuit including a plurality of tables to rewrite a content of a packet header portion.